It is KakaoTV's first original fantasy mystery series and premiered on July 30, 2021, at 20:00 Korean Standard Time (KST), also airing three hours later on another local streaming website, Watcha.

[3] Internationally, it is distributed by iQIYI (in Southeast Asia and Taiwan) and by Viki (in US, Europe, Middle East, Oceania and India).

But this takes a turn when Na Woo soo discovers that the next student to fall into this trap is actually his own friend Kim Il-nam–the lowest scorer of the exam.

And with the help of Hyun-soo (another dead student soul, also the victim of this evil spirit who lost his life and now friends with Ga Doo-shim) they keep Il-nam safe.

[13] On April 27, 2021, media reported that Kim Sae-ron was in talks to star in the series; her agency, Gold Medalist, confirmed that she was positively reviewing the offer.